negative assertions are more powerful/expressive than positive ones. e.g. "Not an enemy" is more powerful than "A friend" - the latter limits the possibilities

negative assertions are more powerful/expressive than positive ones. e.g. "Not an enemy" is more powerful than "A friend" - the latter limits the possibilities a lot. or, #ifndef GONE is more powerful/flexible than #ifdef PRESENT Of course, sometimes one wants exactly that specific things that positive assertions do. But IMO that's rarely the case, it's just going positive seems simpler/easier to think of. one may say, in some system of rules, "Dont's" are more usable than "Do's". Think cultures..